The clinical signs and symptoms of tuberculosis are not specific. Therefore, laboratory methods play a crucial role in establishing the diagnosis, monitoring the therapy and preventing transmission of the disease. Laboratory results must be not only accurate, but also rapidly available. However, the culture techniques most commonly employed world-wide for the diagnosis of tuberculosis are time-consuming. Recently it has been shown that the spent culture supernatant of Mycobacterium tuberculosis and active components (phopholipids and peptides) derived from it can enhance the growth of tubercle bacilli and allow small inocula to initiate growth in liquid culture. The aims of the proposed study are: (1) To evaluate the growth enhancing/resuscitating factors as additives to current liquid and solid medium culture systems using lab strains of M. tuberculosis. Experiments will be carried out in both liquid media (7H9, 7H12B Bactec and MGIT) and solid medium (7H1 1 agar), with different inoculum sizes on both fresh and 01 cultures. Serial dilutions of a fresh culture representing the varying bacterial load of smear positive and smear negative clinical specimens can provide information about the growth enhancing effect of the examined agents, while inocula from old cultures will enable investigation of the resuscitation effect of the agents. (2) To evaluate the effect of opitmal growth enhancing factors on drug susceptible and drug-resistant clinical isolates of M. tuberculosis. The effect of selected phospholipids and peptides (based on the results of the above-detailed experiments) will also be studied both on 50 drug susceptible and drug-resistant clinical isolates. (3) To evaluate the effect of growth enhancing factors on drug susceptibility testing. Drug susceptibility testing will be performed on media containing the growth enhancing factors to rule out any interference and to determine the appropriate MIC values. At the end of the Phase I study the optimal components will be selected for formulation of a new culturel medium with commercial potential for improved diagnosis of tuberculosis.